2009.01.08 Away side jet pt vs. photon pt

Ilya Selyuzhenkov January 08, 2009

Data sets

• pp2006 - STAR 2006 pp longitudinal data (~ 3.164 pb^1)
  Trigger: eemc-http-mb-L2gamma [id:137641]
• gamma-jet[gamma-filtered] - data-driven Prompt Photon [p6410EemcGammaFilter] events.
  Partonic pt range 2-25 GeV.
• QCD jets[gamma-filtered] - data-driven QCD [p6410EemcGammaFilter] events.
  Partonic pt range 2-25 GeV.

Cuts applied

• Di-jet events
• Require to reconstruct photon momentum (no gamma-jet isolation cuts)
• Gamma pt > 7GeV
• L2gamma emulation in Monte-Carlo
• L2gamma triggered pp2006 events

Comments

(concentrated on pre-shower1>0 case
which has better statistics for QCD Monte-Carlo):

• Fig.1, lower plots
  Vertex z distributions from QCD MC and pp2006 data are different in the negative region
• Fig.2, lower plots
  For the away side jet pt < 8GeV region
  QCD Monte-Carlo underestimates the data.
• Fig.4, lower plots
  gamma-jet pt asymmetry plot shows
  that in QCD MC photon and jet pt's are better correlated than in the data
• Fig.5, lower plots
  Most of the differences between QCD MC and pp2006 data for pre-shower1>0 case
  are probably from the lower gamma and jet pt region

Figures

Figure 1: Vertex z distribution

Figure 2: Away side jet pt

Figure 3: Photon pt

Figure 4: gamma-jet pt asymmetry: (pt_gamma - pt_jet)/pt_gamma

Figure 5: gamma pt vs. away side jet pt
1st column: triggered pp2006 data
2nd column: gamma-jet MC (l2gamma trigger on)
3rd column: QCD background MC (l2gamma trigger on)